How to Exercise for Strength Gains & Hormone Optimization | Dr. Duncan French

French’s lab used a classic protocol of 6 sets of 10 reps at ~80% of 1RM on multi-joint lifts like back squats with 2-minute rests. This combination of substantial mechanical load (intensity) and high total reps (volume) reliably elevated testosterone and created a strong metabolic stimulus (lactate, glycogenolysis), which drives muscle growth. Extending rest to 3 minutes or more lowers metabolic stress and leads to less hypertrophy, even if the total work is similar.

French compared 6×10 vs 10×10 at similar intensities. At 10×10, athletes could not maintain the required load, so intensity had to drop, reducing mechanical tension and undermining the hormonal and hypertrophic benefits. This illustrates that past a certain point, adding sets forces intensity down too far and becomes counterproductive. A few very demanding sessions per week (e.g., two 6×10 workouts) are generally sufficient for non-bodybuilders.

Humans are naturally inclined to take more rest and preserve performance on each set, but the physiology of muscle growth favors discomfort: shorter rests keep lactate and other metabolites elevated, amplifying anabolic hormone release and hypertrophic signaling. French emphasizes putting ego aside—accept that you may need to reduce the load to complete the reps on time; the internal stimulus matters more than the number on the bar.

French’s PhD work showed that before a daunting workout, epinephrine and norepinephrine rise in anticipation, and those with the largest catecholamine surge sustain higher force output across the session. Short-term stressors (like a hard lift or even a parachute jump) can transiently elevate testosterone. However, repeated exposure leads to accommodation, and chronic stress without recovery degrades performance and hormones. Learning to deliberately heighten arousal before key efforts, then switch it off afterward, is a key high-performance skill.

Cold (ice baths, cryotherapy) is a real physiological stressor that triggers sympathetic activation, but at the tissue level it can dampen the mTOR pathway and inflammatory signaling needed for muscle growth and strength adaptations. French notes that cold is best reserved for competition phases, when preserving quality and rapid recovery between performances matters more than building muscle. In heavy training or “off-season” periods focused on hypertrophy, frequent ice baths are likely counterproductive.